The G_TYPE_INSTANCE_GET_PRIVATE() macro is deprecated, which generates
a compiler warning since `glib_encoded_version` variable had been
set to the 2.66 version in the main CMakeLists.txt file.

Correct a typo, the finalize() method implementation should chain up
to the finalize() method of its parent, not dispose().

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2661

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2657

The em-format structures with base_init() implementation did not work
properly (preview broke once a message had been replied to), thus partly
revert the change and use a different approach.

Related to https://gitlab.gnome.org/GNOME/evolution-data-server/-/issues/522

Message content retrieval can sometimes fail. Do not claim a problem
on the console only, stop sending instead, to not send empty messages.

Related to https://gitlab.gnome.org/GNOME/evolution/-/issues/2666

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2670

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2659

Header folding can happen only on places where spaces are expected.
While the encoded key data of the Autocrypt header are meant to be
without spaces, the base64 decoding ignores whitespaces, thus it's
okay to have them there. This helps to not pass overly long header
lines in the messages.

Related to https://gitlab.gnome.org/GNOME/evolution-data-server/-/issues/527

The "Remove Key" was not chosen well, even it means to remove it from the message,
it could be read as "remove from the list of the keys" or something. The "Send
without key" is much clearer about the meaning.

Also switch composer mode from HTML to Plain Text when a text/plain
part is used as the message source.

Related to https://gitlab.gnome.org/GNOME/evolution/-/issues/2659

Adds the task type of 'Needs Action' in the Advanced Search feature in the Tasks
view. This task type can already be set in multiple ways, but now it can also be
searched for.

Related specification is RFC 2445 section 4.8.1.11 Status
https://www.ietf.org/rfc/rfc2445.txt

The implementation in the Evolution Data Server already exists.

Tested and confirmed working.

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2665



Signed-off-by: Nico Rikken <nico@nicorikken.eu>

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2664

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2675

(cherry picked from commit 576965911c4919f28fb250bf59e8b5e982874766)

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2677

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2679

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2627

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2663

This way it'll match "Subject and Addresses contain" filter.

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2680

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2685

The "information" icon does not fit to the nature of the failure message.

The only user of it had been evolution-ews and even that did it incorrectly,
sending duplicated mails, thus drop the functionality from the code.

Related to https://gitlab.gnome.org/GNOME/evolution-ews/-/issues/259

Servers with "save-schedule" capability send meeting change notifications
on their own. When deleting a meeting and sending specific cancellation
mail, it doesn't make much sense to let the server send another cancellation
mail by itself, due to the deletion, thus let the calendar backend know
that it can avoid sending the message.

The Flathub is going to use it, thus provide some colors.
https://docs.flathub.org/blog/introducing-app-brand-colors/

The GSettings is used only for the development build, thus declare
it only when really needed.

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2632

It's meant to be used by the linker, not by the compiler, thus keep
it only for the linker flags. Clang claims the argument is not used.

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2672

The wiki.gnome.org might be removed in the future, thus replace
the URL with the new home.

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2691

(cherry picked from commit d55eac015f1d383f66ad4f40326e48fb082d65b6)